This request is for funds to purchase a single photon Nikon A1Rsi confocal microscope with total internal reflection fluorescence (TIRF) capabilities and two GaSP detectors. This instrument will be housed within the Pharmacy Live Cell Imaging Facility (PLCIF) in the College of Pharmacy at Purdue University. The mission of this facility is to provide access to confocal and TIRF microscopy, along with image analysis, to all research groups within the College of Pharmacy at Purdue University. Confocal and TIRF microscopy are essential services provided by the facility, the current facility houses an 8.5-year old Nikon confocal and TIRF microscope. The prime reasons for this application are to replace the aging Nikon confocal instrument currently in the PLCIF and provide the critically needed instrument time to the NIH supported users of the PLCIF. The PLCIF began operations in 2010 and has since become an integral part of the research community with more than 23 PHS funded groups within the College of Pharmacy using the facility, as well as several PHS supported projects with investigators in nearby buildings in other colleges. The PHS funded user base within the College and nearby buildings continues to expand, and the instrument time available on the aging microscope has become a major limiting factor in the utility of the center. For instance, a major laser repair was needed in 2017 to the existing microscope meaning the instrument time was lost for approximately 6 weeks. Secondly, a 60X objective necessary for both TIRF and some confocal imaging needed to be replaced in 2017 as well. While the objective down time was only about 3 weeks, this lead to frustration for some users and delays in data acquisition. Another hurdle during instrument downtime (as well as a challenge throughout normal operations) has been proximity of the College of Pharmacy to other imaging capabilities on campus. The PLCIF is located within the Pharmacy building on the north side of campus whereas other core imaging facilities are located on the south side of Purdue University?s campus. This distance, about 1 mile, is a significant hurdle for transporting live cell and animal based experiments due to both weather and transport related effects on sample viability. Thus, the PLCIF is strategically placed on campus to enable users in the College of Pharmacy and nearby research buildings to perform live cell and animal imaging experiments with minimal disruption to sample preparation and work flow. The acquisition of a basic single photon confocal microscope will be a tremendous addition to the PLCIF and will help to ensure capabilities for single photon confocal microscopy and TIRF for years to come.